This time, the predictions of horrific traffic tie-ups turned out to be true.

At its worst, bumper-to-bumper traffic slogged for six miles yesterday from east of the Woodrow Wilson Bridge in Maryland as construction crews shifted a second stretch of the Capital Beltway to make way for a new, wider span.

Delays during similar work on the outer loop last month didn't live up to apocalyptic warnings. But yesterday afternoon and evening, it took two hours to cross the Potomac River. Frustrated, sweaty drivers pulled over to smoke, take bathroom breaks or stretch their legs and curse their fates.

Long-distance travelers, who were reminded of the construction en route and urged to travel around it, were also fed up. "I feel like going home," said Joseph Maratto of New Jersey, who was plotting a new course to Lorton at a rest stop in Laurel.

Construction crews laying asphalt 21/2 feet thick were slowed somewhat by temperatures that reached 95 degrees. Bridge officials still project that the weekend's work will end in time for tomorrow morning's commute.

"We still feel comfortable that unless something happens, we'll be finishing sometime on Sunday and the lanes will all be open by Monday," said John Undeland, a spokesman for the 7.5-mile project, the biggest and most costly on the East Coast.

But don't expect today to bring much relief. Although traffic is typically 12 percent lighter on Sundays, bridge officials said drivers still should find another way.

Last month, the public was warned of 15-mile jams and 90-minute delays on Interstate 95 and the Beltway during the first phase of paving on the outer loop. But traffic moved more smoothly than during the typical weekday commute.

For two weeks before this weekend's lane closures, officials again warned drivers in ominous radio broadcasts -- from Baltimore to the beaches -- to avoid the bridge.

Officials blamed yesterday's gridlock on several factors. Among them: uninformed drivers from outside the Washington region; local motorists who doubted or ignored the second round of warnings in what bridge officials called "message fatigue"; and the tendency of both groups of drivers to rubberneck as they passed the construction area.

The inner loop of the Beltway normally has about 13 percent more traffic on a typical Saturday than the outer loop. Adding to the problem, bridge officials said they had less flexibility to divert drivers on the Maryland side of I-95.

When a piece of the outer loop was realigned last month, transportation officials set up a six-mile detour for motorists to avoid the bridge. This time, the minimum detour was 25 miles for drivers traveling on the east side of the Beltway.

"We knew it made a difference, but we're finding out just how big of a difference," Undeland said.

The paving is part of the $2.43 billion, 11-year project to replace the aging bridge that was built to carry less than half of the nearly 200,000 vehicles that now cross each day.

All but one lane of the inner loop of the Beltway will remain closed today from just east of Interstate 295 in Maryland to just beyond the Route 1 interchange in Virginia. Bridge officials are advising drivers to avoid the worst backups by using Route 301 through Maryland, the western half of the Beltway or I-395 through the District. These detours are not without their own headaches: Traffic on 301 was backed up for a time for five miles before the Harry W. Nice Memorial Bridge, which connects southern Charles County with Virginia.

As early as 8 a.m., motorists crossing the Wilson Bridge were jammed for two to three miles, in line with a typical weekday commute. By 10 a.m., officials were tracking backups of six miles, which continued until about 5 p.m.

From Beltsville, traffic moved smoothly on the inner loop. The backups began just after the exit for Route 5 near Camp Springs, where traffic resembled the drive-up window at a fast-food restaurant rather than the East Coast's major north-south highway. It took a driver two hours and 41 minutes to drive the six miles to Route 1 in Virginia. As vehicles were funneled from four lanes to one, some cars stalled or pulled over onto the shoulder in the tropical temperatures.

The weather also affected the pace of the paving. Two crews were redirecting a half-mile section of the inner loop, which will allow workers to complete an overpass at South Washington Street in Alexandria.

The job required twice as much asphalt as last month's to build up the old road to meet the curve of the new one. The crews poured layers of steaming, 300-degree asphalt. The thick, gravelly mixture must cool to less than 150 degrees between each layer. And the heat and humidity didn't help.

The first warnings to long-distance travelers yesterday were posted along I-95 at the New York-Connecticut line. In New Jersey, Maratto had planned to take I-95 all the way to Lorton to catch the car train to Florida. After seeing the signs on the highway, he pulled off at the Maryland Welcome Center to study a map and seek advice.

For the Fulton family of 10, the change of course just meant choosing a different sightseeing stop on the way home to South Carolina. At the Laurel rest stop, Ashley Fulton, the family navigator and spokeswoman, said the caravan of four cars had decided to skip the White House in favor of Arlington National Cemetery or another attraction to the west of the District.

John and Donna Taylor of Philadelphia were driving yesterday to the Outer Banks of North Carolina to meet their family. Their relatives left Friday, and as he and his wife searched for directions at the rest stop, John Taylor said, "We should have went last night."

Staff writer Michael Alison Chandler contributed to this report.

Motorists who failed to heed the construction warnings contend with the long backup on the inner loop of the Capital Beltway.At a rest stop in Laurel, Mariellen Somerville helps motorists find ways around the Wilson Bridge.